A.Word.A.Day--aphotic

It's that time of the year again when you get to don your word-sleuth hat.
There's something common among this week's words but we're not telling --
it's your task to find the property that applies to all five words this week.
Each day this week brings a new word that on the surface may not appear to
share a trait with the others, but does.

Will you be first to solve the mystery theme? If you think you have the
answer, scribble it down and email it to wordsATwordsmith.org (replace
AT with @). Only one answer per person, please.